Wither the Wolf, Behold the Coywolf

According to werewolf legends, some humans can suddenly "shapeshift" or transform into wolves. But in real life, wolves are disappearing in large numbers and being replaced by coywolves. These coyote-wolf hybrids are now common in parts of the U.S.

A new study in the Journal of Mammalogy proves that such interbreeding is taking place. Lead author Christine Bozarth of the Smithsonian Conservation Biology Institute and her colleagues collected coyote scat (aka poop) and conducted DNA studies on it. The DNA revealed that coyotes moving into Northern Virginia stopped along their route to breed with native Great Lakes wolves.

People are to blame for the coyotes moving in the first place, since the changes inflicted on North American ecosystems over the past 150 years, due to hunting, habitat encroachment, pollution and other causes, have pushed coyotes out of their native homelands of the plains and southwestern deserts. Now coyotes are on the move and seeking other places to live.

The poop trail left behind by the animals reveals that coyotes have been migrating eastward along two main routes — one through the South and another through the northern U.S. The new DNA information shows that Virginian coyotes are most closely related to coyote populations in western New York and Pennsylvania.

While trekking northward, they eventually encountered the Great Lakes wolves and interbred before converging again on the East Coast. They then gradually headed south along the Appalachian Mountains toward what is considered the Mid-Atlantic region, to an area centered around Virginia.

"The Mid-Atlantic region is a particularly interesting place because it appears to mark a convergence in northern and southern waves of coyote expansion," Bozarth was quoted as saying in a press release. "I like to call it the Mid-Atlantic melting pot."

Hybridization between canid species is thought to be rare, but as this latest study proves, it can occur. Hybridization may happen when individuals have trouble finding mates from their own species.

"This does not mean that we have massive, wolf-like coyotes roaming around here in Virginia," Bozarth said. "Coyotes with wolf ancestry have differently shaped jaws, which may allow them to fill different ecological niches. They tend to hunt small prey and scavenge large game, so hybrid coyotes might be helpful in controlling the overly abundant deer population."

That's the good news (although not for the individual deer). The bad is that while coyote populations have been expanding, wolf populations have become endangered. Hybridization with coyotes is now a major threat to the recovery of wolves.

"For the past decade, our lab has developed and used noninvasive techniques to monitor and survey rare and endangered species in various regions of the world, and in this study, we were able to show that noninvasive techniques can also be an effective tool for tracking the origins and movement patterns of this elusive canid," co-author Jesús Maldonado, an SCBI research geneticist, was quoted as saying. "The admixed coyotes have also been found further south, into North Carolina, which brings the hybridized coyote into the range of the critically endangered red wolf, further complicating the issue."

Should the interbreeding continue, how many true North American wolves will we have left in the wild? Probably not many.